Asynchronous mid-infrared broadband optical parametric oscillator for dual-comb spectroscopy Zhaowei Zhang, Chenglin Gu, Jinghua Sun, Chingyue Wang, Tom Gardiner and Derryck T. Reid EPJ Web of Conferences, 41 (2013) 10008 Published online: 13 March 2013 DOI: 10.1051/epjconf/20134110008